The present invention relates to a novel process for producing linalool. More particularly, it relates to a process for producing linalool by a hydrogenation of O-linalyl-N,N-dimethyl hydroxylamine in the presence of the specific catalyst.
Linalool is the useful compound as the starting material for producing vitamins.
The starting material O-linalyl-N,N-deimethyl hydroxylamine can be easily economically produced by a telomerization of isoprene and dimethylamine and a reaction of the resulting nerylamine with hydrogen peroxide and a thermal rearrangement of the resulting nerylamine oxide.
It has been known that linalool is produced by a reduction of O-linalyl-N,N-dimethyl hydroxylamine with zinc and acetic acid. However, an industrially advantageous hydrogenation has not been known.
The inventors have studied to carry out the hydrogenation of O-linalyl-N,N-dimethyl hydroxylamine in the presence of a catalyst of nickel, cobalt or copper whereby dihydrolinalool is obtained. The inventors further studied to carry out the hydrogenation of O-1,2-dihydrolinalyl-N,N-dialkyl hydroxylamine in the presence of a catalyst of copper chromite whereby dihydrolinalool is obtained in high yield.
However, it has been impossible to obtain linalool by a hydrogenation with a catalyst because the double bond between carbon atoms at 1- and 2-positions of O-linalyl-N,N-dimethyl hydroxylamine is easily hydrogenated, though linalool is quite important.